Transport apparatus and vacuum processing system using the same

ABSTRACT

This invention provides a transport apparatus having a simple configuration that can reduce its turning radius and transport semiconductor devices at high speed. The transport apparatus comprising the first and second arms having at a first end of each thereof a rotary drive shaft being arranged coaxially, and third and fourth arms rotatably linked at respective the first ends thereof to the respective second ends of the first and second arms. The second ends of the third and fourth arms are supported around centers of coaxially arranged spindles, respectively. The transport apparatus further comprises an articulating mechanism having an attitude control mechanism adapted to apply rotary forces with opposite phases to the respective spindles arranged at the third and fourth arms.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transport apparatus for bringing asemiconductor substrate or the like into a vacuum processing chamber andcarrying it out from the chamber to a predetermined position.

2. Description of the Related Art

In recent years, there has been a strong demand for precisionsemiconductor devices with critical dimensions. Systems formanufacturing such semiconductor devices are then required to improvethe throughput and reduce the foot print necessary for installing thesystem.

In view of these requirements, there have been proposed multi-chambersystems and transport apparatuses comprising a transport chamberarranged at the center and a plurality of processing chambers arrangedaround the transport chamber and connected thereto by way of respectivegate valves so that various processing operations may be conducted invacuum atmosphere in a coordinated manner (see the publications ofJapanese Patent Nos. 2733799 and 2808826).

FIG. 16 of the accompanying drawings is a schematic plan view of such aknown transport apparatus (as disclosed in Japanese Patent Laid-OpenPublication No. Hei. 4-279043), illustrating a principal part thereof.

Referring to FIG. 16, in the transport apparatus 100, the rotary forcegenerated by a drive source (not shown) is transmitted to a drive shaft101, to a drive gear 102 secured to the drive shaft 101 and then to adriven shaft 104 by way of driven gear 103 engaged with the drive gear102.

A first arm 105 is fitted to the drive shaft 101 and a third arm 107 islinked to the end of the first arm 105 so as to be rotatable around itsrotary shaft 106.

On the other hand, a second arm 108 is fitted to the driven shaft 104and a fourth arm 110 is linked to the end of the second arm 108 so as tobe rotatable around its rotary shaft 109.

A movable pulley 111 is fitted to the third arm 107 so as to berotatable coaxially around the rotary shaft 106. The movable pulley 111is linked to a fixed pulley 112 that is fixed coaxially with the drivenshaft 101 by way of a belt 113. The diameter of the movable pulley 111and that of the fixed pulley 112 show a ratio of 1:2.

Mating gears 116, 114 are rotatably fitted to the respective ends of thethird and fourth+arms 107 and 110. The mating gears 116, 114 are engagedwith each other and fitted to a substrate holder 115.

With the known transport apparatus 100 having the above described linkmechanism, as the drive shaft 101 is driven to rotate, the substrateholder 115 is moved along a straight line 1 rectangularly intersectingthe straight line connecting the center of the drive shaft 101 and thatof the driven shaft 104 (to be referred to as “transport line”hereinafter) in a horizontal plane and passes through a position wherethe first arm 105 and the second arm 108 form an angle of 180° (to bereferred to as “dead point” hereinafter).

In the transport apparatus 100, the drive shaft 101 and the driven shaft104 are rotatably fitted to a support (not shown) in such a way that thesubstrate holder 115 is driven to rotate around the drive shaft 101 byanother drive source (not shown).

With the above described known transport apparatus 100, however, sincethe substrate holder 115 is driven to rotate around the drive shaft 101,it does not rotate around the center of the arms that is theintersection O of the straight line m connecting the center of the driveshaft 101 and that of the driven shaft 104 and the transport line 1 whenthe first through fourth arms 105, 107, 108 and 110 are folded to thedead point.

This means that, with the above described known transport apparatus 100,it is difficult to reduce the minimum turning radius and hence the innerdiameter of the transport chamber. Then, by turn, it is difficult todimensionally reduce the entire semiconductor manufacturing system.

While the throughput of a semiconductor manufacturing system can beimproved effectively by increasing the operating speed of the transportapparatus thereof, the operating torque of the drive source cannot beraised to increase the operating speed of the transport apparatus whenboth the drive shaft 101 and the driven shaft 104 are operated by meansof a single drive source as in the case of the above described knowntransport apparatus. This problem is due to transmission loss of rotaryforce.

These problems may be solved by using first and second drive shafts thatare arranged coaxially and driven independently by respective drivesources. Then, however, since the mating gears 114, 116 that constitutean articulating mechanism are juxtaposed, the angle of rotation of thethird arm 107 relative to the first arm 105 and that of the fourth arm110 relative to the second arm 108 are not proportional to the angle ofrotation of the first arm 105 and that of the second arm 108respectively. Therefore, the rotary motion of the third arm 107 and thatof the fourth arm 110 are not synchronized with the rotary motions ofthe first and second arms 105, 108 to make it difficult to move thesubstrate holder 115.

While these problems may be avoided by providing a complex correctionmechanism, such a mechanism inevitable raise the number of componentsand that of assembling steps.

FIG. 17 of the accompanying drawings is a schematic plan view of anotherknown transport apparatus (as disclosed in Japanese Patent Laid-OpenPublication No. Hei. 9-283588), illustrating a principal part thereof.

Referring to FIG. 17, with this known transport apparatus 200, therotary forces generated independently by a pair of drive sources (notshown) are transmitted respectively to a first drive shaft 201 and asecond drive shaft 202 that are arranged coaxially.

A first arm 203 is fixed to the first drive shaft 201 and a third arm205 is linked to the end of the first arm 203 so as to be rotatablearound its rotary shaft 207.

On the other hand, a second arm 204 is fixed to the second drive shaft202 and a fourth arm 206 is linked to the end of the second arm 204 soas to be rotatable around its rotary shaft 208. The length of the secondarm 204 and that of the fourth arm 206 are made equal to those of thefirst and third arms 203 and 205, respectively.

A first pulley 209 is fixed to the third arm 205 so as to be rotatablearound the rotary shaft 207 coaxially. A second pulley 210 is coaxiallyfixed to the second drive shaft 202. An endless drive belt 211 is woundaround the first pulley 209 and the second pulley 210. A dead pointescape mechanism 212 is formed by the first and second pulleys 209, 220and the drive belt 211.

A first mating pulley 215 is fixed to the end of the third arm 205 and asecond mating pulley 216 having a diameter same as that of the firstmating pulley 215 is fitted to the end of the fourth arm 206. The firstand second mating pulleys 215, 216 are rotatably fitted to a substrateholder 217 by way of respective rotary pins 219, 220. A restraint belt221 is wound around the restraint pulleys 215, 216 to substantially forma FIG. “8”. The first and second mating pulleys 215, 216 and therestraint belt 221 form an attitude control mechanism 222.

With this known transport apparatus 200 having the above described linkmechanism, the substrate holder 217 is driven to move straight byrotating the first drive shaft 201 and the second drive shaft 202reversely relative to each other on the transport line 222 passingthrough the bisector of the angle between the third arm 205 and thefourth arm 206 running through the center of the first drive shaft 201and the second drive shaft 202, the angle being restraint by therestraint belt 221.

With this known transport apparatus 200, if the first arm 203 and thesecond arm 204 are located on dead line 223 where the angle between thefirst arm 203 and the second arm 204 becomes equal to 180°, the rotaryforce of the second drive shaft 202 is transmitted to the third arm 205by way of the drive belt 211 and the first pulley 209 to cause thesubstrate holder 217 to pass through the dead line 223.

Additionally, with this known transport apparatus 200, since the fourtharm 206 is linked to the second arm 204 by means of a pin (whereas thethird arm 205 is not only linked to the first arm 203 by means of a pinbut also restrained by the second drive shaft 202 by way of the firstpulley 209, the drive belt 211 and the second pulley 210), the firstpulley 209 and the third arm 205 try to rotate relative to the first arm203 by an angle of 2 θ (that is, twice the rotary angle θ of the secondarm 204) when the first drive shaft 201 and the second drive shaft 202are driven to rotate in opposite senses by an angle of θ.

On the other hand, since the two mating pulleys 215, 216 of the attitudecontrol mechanism 222 are juxtaposed, the angle of rotation of the thirdarm 205 relative to the first arm 203 and that of the fourth arm 206relative to the second arm 204 are not proportional to the angle ofrotation θ of the first and second arms 203 and 204. In other words,since the angle of rotation of the mating pulley 215 is equal to that ofthe mating pulley 216, the former angles of rotation are not equal totwice of the angle θ and the constant of proportionality can fluctuatearound 2 depending on the latter angles of rotation. Because of thediscrepancy that can arise to the angle of rotation of the third arm dueto the different mechanism, the substrate holder 217 may not be helduniformly relative to the transport line 222; thereby, deteriorating thestraightness of the movement. Additionally, the substrate holder 217 mayhave difficulty in moving.

It is known to divide the drive belt 211 and arrange tension coilsprings between them in order to avoid the above identified problems. Itis also known to provide a tension regulating mechanism for suppressingthe expansion/contraction of the drive belt 211 by arranging a pluralityof tension pulleys between the first pulley 209 and the second pulley210.

However, even the known transport apparatus 200 is provided with such aknown tension regulating mechanism, the first pulley 209 and the secondpulley 210 can show a phase difference because of the difference in theelongation due to heat of the drive belt 211 and the first arm 203 sothat the dead point escape mechanism 212 can still adversely affect thelinear movement of substrates. This problem is particularly remarkablewhen the arms of the link mechanism and the drive belt 211 are made longin order to increase the distance for transporting substrates.Additionally, the tension regulating mechanism involves a problem ofrequiring a long and cumbersome operation for assembling it andregulating the tension.

It is also known to provide a mechanism designed to equalize the angleor rotation of the fourth arm 206 relative to the second arm 204 andthat of the third arm 205 relative to the first arm 203 by using acam-shaped pulley for the first pulley 209 or the second pulley 210 andrestricting the rotary motion of the third arm 205 in order to ensure alinear movement of the known transport apparatus 200.

However, if such a cam-shaped pulley is used for the transport apparatus200, the process of preparing the cam-shaped pulley becomes a cumbersomeone and requires an increased number of parts to consequently raise thecost of the mechanism and hence that of the semiconductor manufacturingsystem including the transport apparatus 200.

While it may be conceivable to provide a mechanism for adjusting thelength of the first arm 203, again the process of preparing such amechanism is cumbersome and requires an increased number of parts toconsequently raise the cost of the mechanism as in the case of thetension regulating mechanism and the pulley mechanism, which aredescribed above.

SUMMARY OF THE INVENTION

Thus, it is an object of the present invention to provide a transportapparatus having a simple configuration that involves a small turningradius and provides a high transport speed.

Another object of the invention is to provide a transport apparatus thatcan ensure a linear movement of substrates by eliminating the adverseeffects of the dead point escape mechanism on the attitude controlmechanism without raising the number of parts and entailing a cumbersomeassembly and adjustment process.

With the transport apparatus as provided in the first embodiment of thisinvention, since drive shaft of the first arm and that of the second armare arranged coaxially, the minimum turning radius can be reduced thanever in a state where the first through fourth arms are arranged at thedead point.

Additionally, with the transport apparatus as provided in the firstembodiment of this invention, since the opposite ends of the third andfourth arms are linked to the respective spindles that are arranged alsocoaxially, the drive shafts of the third and fourth arms can be drivento rotate without requiring a complex correction mechanism for changingthe arm length so that the first through fourth arms can be operated athigh speed although the transport apparatus has a simple configuration.

Furthermore, with the transport apparatus as provided in the firstembodiment of this invention, the spindles of the third and fourth armsare driven to rotate with opposite phases so that substrates can bemoved linearly along the predetermined transport line without entailingproblems including the problem of unintended rotation of the carrierfitted to the articulating mechanism and the carrier can be movedsmoothly at and near the dead point.

The unintended revolution of the carrier can be completely preventedfrom taking place when the rotary forces applied respectively to thespindles of the third and fourth arms with opposite phases are madeequal in the first embodiment of this invention.

The overall configuration of the transport apparatus as provided in thefirst embodiment of this invention can be further simplified when theattitude control mechanism is provided with a power transmissionmechanism for transmitting rotary forces respectively to the spindles ofthe third and fourth arms with opposite phases.

The articulating mechanism of the transport apparatus as provided in thefirst embodiment of this invention can be made thin and lightweight whenthe above-mentioned attitude control mechanism comprises pulleys andbelts as defined above because the attitude control mechanism can thenbe made to have a low profile and a small weight.

When the attitude control mechanism of the transport apparatus asprovided in the first embodiment of this invention comprises first andsecond restraint pulleys fixed respectively to the spindles of the thirdand fourth arms, a third restraint pulley juxtaposed with the first andsecond restraint pulleys, a first restraint belt arranged so as to driveeither the first restraint pulley or the second restraint pulley and thethird restraint pulley to rotate in phase, and a second restraint beltarranged so as to drive either the first restraint pulley or the secondrestraint pulley and the third restraint pulley to rotate with oppositephases, it is possible to reliably transmit rotary forces respectivelyto the spindles of the third and fourth arms with opposite phases,although the transport apparatus has a simple configuration.

When the attitude control mechanism of the transport apparatus asprovided in the first embodiment of this invention comprises sprocketsand chains as defined above, it is made free from slippery motions andaffected minimally by thermal expansions.

When the attitude control mechanism of the transport apparatus asprovided in the first embodiment of this invention comprises gears asdefined above, the transport apparatus can be assembled and regulated ina simple way without requiring the need of regulating tension unlike thecase of using belts.

When the transport apparatus as provided in the first embodiment of thisinvention is equipped with an additional power transmission mechanismcomprising a drive pulley fixed to the drive shaft of the first orsecond arm, a driven pulley secured to an end of the spindle of thethird or fourth arm, and a belt wound around the drive pulley and thedriven pulley, the power of the drive source is efficiently transmittedto each of the arms by way of the additional power transmissionmechanism so that the transport apparatus can be operated more smoothlyat high speed.

As described above, in the first embodiment of this invention, it ispossible to provide a compact vacuum processing system that cantransport objects to be processed at high speed.

On the other hand, with the transport apparatus as provided in thesecond embodiment of this invention, a pair of spindles for coaxiallyand respectively supporting a pair of driven arms at respective endsthereof and a rotary member of the attitude control mechanism arearranged with a predetermined positional relationship on the substrateholder for holding predetermined substrates and a second link mechanismis formed by adding a separate link member as dead point escapemechanism in order to allow the substrate holder to escape the deadpoint of the first parallel link mechanism. Thus, the rotary motions ofthe paired driven arms are synchronized by the rotary member of theattitude control mechanism to eliminate any relative displacement of thephases of the driven arms. Additionally, the expansion/contraction thatcan arise in the second link mechanism due to external force and/or heatcan be equalized with the expansion/contraction that arises in the firstlink mechanism in an easy way of making the link members from the samematerial of the first link members if compared with, the prior art sothat any displacement of the phase of each of the paired driven armsrelative to that of the corresponding one of the paired drive arms canbe eliminated.

As a result, with the transport apparatus as provided in the secondembodiment of this invention, the substrate holder can be made toreliably move straight because the attitude control mechanism canoperate properly, eliminating any adverse effects that the dead pointescape mechanism can otherwise exert on the first parallel linkmechanism.

With the transport apparatus as provided in the second embodiment ofthis invention, when all the inter-joint distances of the paired drivearms and the paired driven arms of the first link mechanism are madeequal to each other and the inter-joint distance of the link members ofthe second link mechanism is made equal to that of the first linkmechanism, while the link member of the second link mechanism is made torun in parallel with one of the paired drive arms, the pairs of drivenarms can be made to rotate by a same angle of rotation relative to thepaired drive arms. In addition, the expansion/contraction that can arisein link member of the second link mechanism due to heat can be equalizedwith the expansion/contraction that arises in the paired drive arms andthe paired driven arms of the first link mechanism by selecting aparallel link mechanism for both the first link mechanism and the secondlink mechanism. This can ensure a stable linear movement of thesubstrate holder.

With the transport apparatus as provided in the second embodiment ofthis invention, when the second link mechanism is formed by using thelink member, one of the drive arms, and one of the driven arms, the deadpoint escape mechanism can be realized simply by adding the link member.Therefore, the use of members including pulleys for the dead pointescape mechanism and the provision of a mechanism for regulating thedead point escape mechanism of the prior art are no longer necessary.Then, the transport apparatus can be realized with a reduced number ofcomponents and hence can be assembled in a simple manner so that the useof a complex regulation procedure is no longer necessary to reduce thecost of the entire semiconductor manufacturing system including thetransport apparatus.

With the transport apparatus as provided in the second embodiment ofthis invention, when the arm section of the link member of the secondlink mechanism has a length between ⅕ and ⅓ of the length of the paireddrive arms of the first link mechanism and shows an angle of inclinationbetween 20° and 40°, the first link mechanism and the second linkmechanism does not come to the dead point simultaneously so that thefirst link mechanism can smoothly and advantageously pass through thedead point.

Finally, with the transport apparatus as provided in the secondembodiment of this invention, when the substrate holder comprises aplurality of holding sections and the attitude control mechanism isarranged at a position where the rotary member is separated from theseholding sections by a same and identical distance, the rotary member andthe power transmission members by which the rotary member is fitted tothe paired driven arms will expand/contract by a same amount due to heatif the holding members of the substrate holder are made to carryrespective heated substrates because they are evenly heated by thesubstrates. Then, the substrate holder can accurately move straight.

As described above, in the second embodiment of this invention, it ispossible to provide a vacuum processing system that can accurately movestraight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a vacuum processing systemaccording to the present invention.

FIG. 2 is a plan view of an embodiment of a transport apparatusaccording to the first embodiment of this invention, illustrating itsconfiguration.

FIG. 3A is a cross sectional side view of an attitude control mechanismof an articulating mechanism of the embodiment of FIG. 2.

FIG. 3B is a cross sectional view taken along line A-A in FIG. 3A.

FIG. 3C is a cross sectional view taken along line B-B in FIG. 3A.

FIGS. 4A through 4D are schematic illustrations of an operation ofreplacing a treated semiconductor wafer with an untreated semiconductorwafer in a vacuum processing vessel by using the embodiment of FIG. 2(Part 1).

FIGS. 5A through 5C are schematic illustrations of an operation ofreplacing a treated semiconductor wafer with an untreated semiconductorwafer in a vacuum processing vessel by using the embodiment of FIG. 2(Part 2).

FIG. 6 is a cross sectional view of an alternative attitude controlmechanism that can be used for the embodiment of FIG. 2.

FIG. 7 is a cross sectional view of another alternative attitude controlmechanism that can be used for the embodiment of FIG. 2.

FIGS. 8A through 8C are cross sectional views of still anotheralternative attitude control mechanism that can be used for theembodiment of FIG. 2.

FIG. 9 is a plan view of another embodiment of the transport apparatusaccording to the invention.

FIG. 10 is a plan view of still another embodiment of the transportapparatus according to the invention.

FIG. 11 is a plan view of an embodiment of a transport apparatusaccording to the second the invention, illustrating its configuration.

FIG. 12 is a side view of the embodiment of the transport apparatus ofFIG. 11 as viewed in the direction of allow Y in FIG. 11.

FIG. 13A is a cross sectional side view of an attitude control mechanismof an articulating mechanism of the embodiment of FIG. 12.

FIG. 13B is a cross sectional view taken along line C-C in FIG. 13A.

FIG. 13C is a cross sectional view taken along line D-D in FIG. 13A.

FIGS. 14A through 14D are schematic illustrations of an operation of afirst parallel link mechanism and that of a dead point escape mechanism(a second parallel link mechanism) of the embodiment of FIG. 11.

FIG. 15 is a plan view of still another embodiment of the transportapparatus according to the invention.

FIG. 16 is a plan view of a known transport apparatus.

FIG. 17 is a plan view of another known transport apparatus,illustrating main parts thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described indetail below with reference to the accompanying drawings.

FIG. 1 shows a schematic illustration of a vacuum processing systemaccording to the present invention.

The vacuum processing system 1 has a transport chamber 1A arranged atthe center, and has a loading/unloading chamber 1B and first to fifthprocessing chambers 1C-1G arranged around the transport chamber 1A. Thetransport chamber 1A, loading/unloading chamber 1B, and first to fifthprocessing chambers 1C-1G are hermetically sealed and connected.Further, they can keep their vacuum atmospher separately.

In the conveying chamber 1A, a transport apparatus 2 according to thepresent invention is installed to bring a semiconductor wafer 13 intothe loading/unloading chamber 1B and the first to fifth processingchambers 1C-1G and carrying it out from the chambers freely.

FIG. 2 is a plan view illustrating the configuration of an embodiment ofthe transport apparatus according to the first embodiment of thisinvention.

Referring to FIG. 2, the transport apparatus 2 according to the presentembodiment has first and second drive shafts 11, 12 which are arrangedcoaxially. Independent first and second driving sources M1, M2 transmitrotary forces in the clockwise and counterclockwise directions to thesedrive shafts 11, 12, respectively, to rotate the first and second driveshafts 11, 12.

A first arm 21 is fixed to the first drive shaft 11, while a second arm22 is fixed to the second drive shaft 12.

At the ends of the first and second arms 21, 22, third and fourth arms23, 24 are mounted with bearings(not shown), for example, so that theycan smoothly rotate around spindles 23 a, 24 a, respectively.

The ends of these third and fourth arms 23, 24 are connected to anarticulating mechanism 3 that has an attitude control mechanism to bedescribed later.

In the present embodiment, all the first to fourth arms 21-24 have thesame length (distance between rotation axes). Hereafter, thefirst-fourth arms 21-24 are referred to as an arm 20 as necessary.

FIG. 3A is a side sectional view of the attitude control mechanism ofthe articulating mechanism according to the present embodiment; FIG. 3Bis a sectional view taken along the A-A line in FIG. 3A; and FIG. 3C isa sectional view taken along the B-B line in FIG. 3A.

As shown in FIG. 2 and FIG. 3A, the articulating mechanism 3 has aholder 30 and this holder 30 has a carrier 31 on which a semiconductorwafer 13 is mounted.

In the present embodiment, a first carrier 31 a is attached to theholder 30 on the side of the first and second drive shafts 11, 12, whilea second carrier 31 b is symmetrically attached to the opposite side ofthe holder 30. In this way, the transport apparatus can carry twosemiconductor wafers 13 at a same time.

In the present embodiment, the holder 30 of the articulating mechanism 3includes an attitude control mechanism 4 that is described below.

Referring to FIG. 3A, this attitude control mechanism 4 has first tothird cylindrical restraint pulleys 41, 42 and 43.

The first restraint pulley 41 is fixed to the end of the third arm 23 onthe side opposite to the side where the first arm 21 is connected. Thispulley rotates around a spindle 33 a mounted on, for example, the upperpart of the holder 30. This first restraint pulley 41 allows the thirdarm 23 to rotate in parallel to the plane including a transport line L,which will be described later.

Meanwhile, the second restraint pulley 42 is fixed to the end of thefourth arm 24 on the side opposite to the side where the second arm 22is connected. This pulley rotates around a spindle 34 a mounted on, forexample, the lower part of the holder 30. This second restraint pulley42 allows the fourth arm 24 to rotate in parallel to the plane includingthe transport line, L.

These first and second restraint pulleys 41, 42 are arranged coaxiallysharing the same rotary axis O₁.

The third restraint pulley 43 is configured to rotate around a spindle35 a in the holder 30, away at a predetermined distance from the firstand second restraint pulleys 41, 42.

The rotary axis O₂ of the third restraint pulley 43 is configured to beparallel with the rotary axis O₁ of the first and second pulleys 41, 42.

The first to third restraint pulleys 41, 42, and 43 have the samediameter.

Referring to FIGS. 3A and 3B, a restraint belt 44 is wound around thefirst restraint pulley 41 and the third restraint pulley 43. Therestraint belt 44 is fixed on the first and third restraint pulleys 41,43 by a, e.g., fastening screw 45. The above configuration makes thefirst restraint pulley 41 and the third restraint pulley 43 rotatesynchronously in phase.

On the other hand, as shown in FIGS. 3A and 3C, a pair of restraintbelts 46, 47 are looped across the second pulley 42 and the third pulley43 so as to substantially form a letter of “8”. These restraint belts46, 47 are fixed on the second and third restraint pulleys 42, 43 by afastening screw 48, for example. This configuration makes the secondrestraint pulley 42 and the third restraint pulley 43 rotatesynchronously with opposite phases.

In the present embodiment of such a configuration, when the third arm 23is rotated by an angle θ in the given direction, the rotary force istransmitted via the first restraint pulley 41 and the restraint belt 44keeping the same phase to the third restraint pulley 43, while therotary force of the third restraint pulley 43 is transmitted via therestraint belts 46, 47 with the opposite phase to the second restraintpulley 42. As a result, the fourth arm 24 fixed to the second restraintpulley 42 rotates in the direction opposite to the third arm 23 by anangle θ.

The operation mechanism of the present embodiment is now explainedbelow.

When the first drive shaft 11 and the second drive shaft 12 are rotatedby a predetermined angle θ in the opposite direction so that the anglemade by the first arm 21 and the second arm 22 decreases from 180degrees, which is the angle made at the dead point, the first arm 21 andthe second arm 22 rotate by the same angle θ in the opposite direction.

In this case, since the first to fourth arms 21-24 form a link mechanismand the first to fourth arms 21-24 have the same length, the third arm23 rotates the predetermined angle θ around the spindle 33 a of thefirst restraint pulley 41, while the fourth arm 24 rotates in theopposite direction by the angle θ around the spindle 34 a of the secondrestraint pulley 42.

As a result, the spindles 33 a, 34 a of the first and second restraintpulleys 41, 42 move on a line L (hereafter, transport line), thatconnects the center of the first and second drive shafts 11, 12 and thecenter of the spindles 33 a, 34 a (see FIG. 2).

In this case, since the third arm 23 and the fourth arm 24 have rotatedwith opposite phases by the same angle θ, the holder 30 of thearticulating mechanism 3 does not rotate around the supporting shafts 33a, 34 a. Therefore, the carrier 31 attached to the holder 30 movesstraight on transport line L.

Meanwhile, in order to return the carrier 31 to the original position,the first drive shaft 11 and the second drive shaft 12 are rotated inthe direction opposite to that described above by the predeterminedangle θ. Then, the operation (reverse to the above operation) isperformed; and the first and second arms 21, 22 return to the deadpoint.

On the other hand, when the first drive shaft 11 and the second driveshaft 12 are rotated in the same direction, the carrier 31 rotates inthe same direction around the first drive shaft 11 and the second driveshaft 12.

The description that follows is the explanation of the carrier 31passing the dead point in the present embodiment.

This embodiment assumes a situation in which the angle formed by thefirst arm 21 and the second arm 22 becomes a little smaller than 180degrees which is the angle formed at the dead point.

In this situation, the first drive shaft 11 is rotated by an angle θ ina given direction and the second drive shaft 12 is rotated by the sameangle θ in the opposite direction to increase the angle formed by thefirst arm 21 and the second arm 22.

At this time, the third arm 23 and the fourth arm 24 are provided withrotary forces in opposite direction to each other. In addition, therotation angle of the third arm 23 relative to the first arm 21 and therotation angle of the fourth arm 24 relative to the second arm 22 aretwice as large as the rotation angle of the first arm 21 and therotation angle of the second arm 22, respectively. Therefore, the thirdarm 23 and the fourth arm 24 rotate against the first arm 21 and thesecond arm 22, and then the carrier 31 smoothly passes the dead point.

FIGS. 4A-4D and FIGS. 5A-5C are diagrams illustrating the operation ofreplacing a treated semiconductor wafer by a untreated semiconductorwafer in the vacuum processing chamber according to the embodiment ofthe invention.

FIG. 4A shows a situation in which an untreated semiconductor wafer 13 ais mounted on the first carrier 31 a and no semiconductor wafer is onthe second carrier 31 b.

First, the first to fourth arms 21-24 being located at the dead point,are rotated, and the second carrier 31 b is directed to the treatedsemiconductor wafer 13 b that has been placed in a predeterminedposition in the vacuum processing chamber (not shown).

Next, as shown in FIG. 4B, the arm 20 is extended to move the secondcarrier 31 b to a wafer exchange position 50 and as shown in FIG. 4C,the arm 20 is returned to the initial position carrying the treatedsemiconductor wafer 13 b on the second carrier 31 b. In this condition,the semiconductor wafers 13, 13 a are mounted on the first and secondcarriers 31 a, 31 b.

Then, referring to FIG. 4D and FIG. 5A, the arm 20 is rotated by 180degrees, pointing the first carrier 31 a to the wafer exchange position50, and the arm 20 is extended to move the first carrier 31 a to thewafer exchange position 50.

After that, as shown in FIG. 5B, after the untreated semiconductor wafer13 a has been left in the wafer exchange position 50, the first carrier31 a is returned to the initial position as shown in FIG. 5C.

As described above, the configuration of the embodiment according to thefirst embodiment of this invention makes the minimum turning radiusprovided when the first to fourth arms 21-24 are located at the deadpoint smaller than that attained by the prior art, because the driveshafts 11, 12 of the first and second arms 21, 22 are arrangedcoaxially.

Further, in the present invention, since the spindles 33 a, 34 a in theends of the third and fourth arms 23, 24 are also arranged coaxially,the rotary force of the drive shafts 11, 12 can be transmitted to thethird and fourth arms 23, 24 without employing a complex correctionmechanism for changing arm length. As a result, it becomes possible tomove fast the first to fourth arms 21-24 with a simple configuration.

Yet further, in the present invention, since the spindles 33 a, 34 a onthe ends of the third and fourth arms 23, 24 are provided with therotary forces with opposite phases, it becomes possible to move thecarrier 31 attached to the holder 30 of the articulating mechanism 3straight along the given transport line L, with no rotation and to movethe carrier 31 smoothly at the dead point and its vicinity.

FIG. 6 is a sectional view of another example of the attitude controlmechanism according to the present invention.

Referring to FIG. 6, in this embodiment, a first bevel gear 51 is fixedto the end of the third arm 23 on the opposite side of its end connectedto the first arm 21, and this first bevel gear 51 can rotate around thespindle 33 a which is installed on, for example, the upper part of theholder 30. The third arm 23 is rotated in parallel to the planeincluding transport line L by the first bevel gear 51.

A second bevel gear 52 is fixed to the end of the fourth arm 24 on theopposite side of its end connected to the second arm 22, and this secondbevel gear 52 can rotate around the spindle 34 a which is installed on,for example, the lower part of the holder 30. The fourth arm 24 isrotated in parallel to the plane including transport line L by thesecond bevel gear 52.

These first and second bevel gears 51, 52 are arranged coaxially sharingthe same rotation axis O.

Further, a third bevel gear 53, which can rotate around the spindle 36 ainstalled orthogonal to the spindles 33 a, 34 a, is installed on, forexample, the inner wall 30 a of the holder 30. This third bevel gear 53engates with the above-mentioned first and second bevel gears 51, 52.

This configuration provides rotary forces with opposite phases to thethird and fourth arms 23, 24.

In the present embodiment, the holder 30 of the articulating mechanism 3does not rotate around the spindles 33 a, 34 a. Thus the carrier 31attached to the holder 30 of the articulating mechanism 3 can preciselymove straight on transport line L.

FIG. 7 is a sectional view of another example of the attitude controlmechanism according to the present invention.

Referring to FIG. 7, in this embodiment, first and second crown gears61, 62 and a pinion gear 63 are used in combination instead of the bevelgears 51-53 shown in FIG. 6 so that the third arm 23 and the fourth arm24 are provided with rotary forces with opposite phases.

In the present embodiment as well, the holder 30 of the articulatingmechanism 3 does not rotate around the spindles 33 a, 34 a. Thus, thecarrier 31 attached to the holder 30 of the articulating mechanism 3 canprecisely move straight on transport line L.

FIGS. 8A-8C are sectional views of another example of the attitudecontrol mechanism according to the present invention.

Referring to FIGS. 8A-8C, a first spur gear 71 is fixed to the end ofthe third arm 23 on the opposite side of its end connected to the firstarm 21, and this first spur gear 71 can rotate around the spindle 33 awhich is installed on, for example, the upper part of the holder 30. Thethird arm 23 is rotated in parallel to the plane including transportline L by the first spur gear 71.

A second spur gear 72 is fixed to the end of the fourth arm 24 on theopposite side of its end connected to the second arm 22, and this secondspur gear 72 can rotate around the spindle 34 a which is installed on,for example, the lower part of the holder 30. The fourth arm 24 isrotated in parallel to the plane including transport line L by thesecond spur gear 72.

These first and second spur gears 71, 72 are coaxially arranged sharingthe same rotation axis O.

Further, a third spur gear 73 that goes into engagement with the firstspur gear 71 is installed on the upper part of the holder 30, while afourth spur gear 74 that goes into engagement with the second spur gear72 and the third spur gear 73 is installed on the lower part of theholder 30.

The engagement of these first to fourth spur gears 71-74 provides rotaryforces with opposite phases to the third and fourth arms 23, 24.

In the present embodiment as well, the holder 30 of the articulatingmechanism 3 does not rotate around the spindles 33 a, 34 a. Thus thecarrier 31 attached to the holder 30 of the articulating mechanism 3 canmove straight precisely on transport line L.

FIG. 9 is a plan view illustrating the configuration of anotherembodiment of the transport apparatus according to the presentinvention. In the description that follows, the common parts are denotedby the same reference numerals and their detailed explanation is notrepeated.

Referring now to FIG. 9, the transport apparatus of the presentembodiment has a separate power transmission mechanism 8 in the secondand third arms 22, 23.

In other words, a first pulley 81 is coaxially fixed to the spindle 23 aof the third arm 23, while a second pulley 82 is coaxially fixed to thedrive shaft 12 of the second arm 22. The diameter of the second pulley82 is the same as that of the first pulley 81.

These first and second pulleys 81, 82 are wound by a drive belt 83 andthis drive belt 83 is fixed by a screw (not shown) on the first andsecond pulleys 81, 82.

The power transmission mechanism 8 of this configuration provides thethird arm 23 in the same phase with the rotary force of the second driveshaft 12 for driving the second arm 22.

In the present embodiment, in addition to the effects described in theprevious embodiments, a smoother and more quick operation becomespossible because the power of the driving sources M1, M2 is efficientlytransmitted to the arms 21-24 by the power transmission mechanism 8. Theother structures and effects, which are all the same as those describedin the previous embodiments, are not explained again here.

FIG. 10 illustrates the configuration of another embodiment of thepresent invention. In the above embodiment, the first and secondcarriers 31 a, 31 b carry two semiconductor wafers 13 at the same time.This invention, however, is applicable to transport apparatuses thatcarry one semiconductor wafer.

As shown in FIG. 10, in the present embodiment, the carrier 32 may beattached to one side in the direction of the movement of the holder 30,and this carrier 32 can carry a single semiconductor wafer 13.

In this case, the carrier 32 may be attached to front side or back sidein the direction of the movement of the holder 30.

However, for use in multi-chamber systems, the carrier 32 may beprovided to the front side relative to the moving direction of theholder 30, so that the moving distance becomes short.

According to the present embodiment of such configuration, it ispossible to make the minimum turning radius smaller than that of theprior art when the first to fourth arms 21-24 are located in the deadpoint as the case of the above embodiment.

In particular, this embodiment is effective to downsize the transportapparatus because it can make the turning radius of the carrier 32small. The other configurations and resulting effects are not repeatedhere because they are the same as those described so far.

It will be apparent to a person skilled in the art that variousmodifications to the details of construction shown and described may bemade without departing from the spirits of this invention.

For example, it is possible to use sprocket wheels and chains instead ofthe pulleys and belts used in the above-mentioned attitude controlmechanism.

FIG. 11 is a plan view illustrating the preferred structure of atransport apparatus of another embodiment according to the secondembodiment of this invention. FIG. 12 is a side view illustrating theschematic structure of the transport apparatus, seen from direction Y inFIG. 11. Hereafter, the common parts to the first embodiment of thisinvention are denoted by the same reference numerals and detailedexplanations thereof is not repeated.

Referring now to FIG. 11 and FIG. 12, the transport apparatus 2according to the present invention has a first drive shaft 11 and asecond drive shaft 12 which are coaxially arranged. These drive shafts11, 12 rotate in the clockwise and counterclockwise directions, beingdriven by two independent driving sources M1, M2 respectively.

A first arm 21 is fixed to the first drive shaft 11, while a second arm22 is fixed to the second drive shaft 12.

Third and fourth arms (a pair of driven arms) 23, 24 are mounted at theends of the first and second arms(a pair of driving arms) 21, 22 withbearings(not shown), for example, so that the third and fourth arms 23,24 can smoothly rotate around spindles 23 a, 24 a.

These third and fourth arms 23, 24 are coupled to each other at theirends so that their ends can smoothly rotate around a spindle 27 thatwill be described later.

These first to fourth arms 21-24 are made of a aluminum alloy or thelike of which linear expansion coefficient lies in between 23×10⁻⁶ and24×10⁻⁶[/°C.] and have the same length(length between the joints),providing a first parallel link mechanism 1A.

In the case of the present embodiment, a dead point escape mechanism 25is installed in either of the first and second arms 21, 22, for example,the second arm 22, and in either of the third and fourth arms 23, 24,for example, the third arm 23.

This dead point escape mechanism 25 has a link member 25 a, a first linkreceiver 25 b and a second link receiver 25 c. The link member 25 a ismade of the same material as that used in the first to fourth arms 21,22, 23 and 24, and is the same as those arms in length. The first linkreceiver 25 b is fixed in a predetermined position of the second arm 22so as to protrude from the second arm 22 toward the third arm 23. Thesecond link receiver 25 c is fixed in a predetermined position of thethird arm 23 protruding in the same direction as the first link receiver25 b.

The link member 25 a is supported at its ends by a first pin 25 d and asecond pin 25 e which are mounted in the first link receiver 25 b andthe second link receiver 25 c, respectively.

The first pin 25 d is located on straight line L3 inclined clockwise bya mounting angle α relative to the centerline L1 on the second arm 22extending from the center of the second drive shaft 12 to the spindle 24a. At the same time, the first pin 25 d is arranged at a position spacedapart by a length corresponding to a mounting length ratio from thesecond drive shaft 12.

Meanwhile, the second pin 25 e is located on straight line L4 inclinedclockwise by α mounting angle α relative to the centerline L2 on thethird arm 23 extending from the center of the spindle 23 a to thespindle 27. At the same time, the second pin 25 e is arranged at αposition spaced apart by a length corresponding to the same mountinglength ratio from the spindle 23 a.

In this way the first and second pins 25 d, 25 e make the distancebetween the joints of the link member 25 a the same as the length of thearm of the first parallel link mechanism 10A. The link member 25 a alongwith the first arm 21 constitutes a second parallel link 10B via thefirst pin 25 d on the second arm 22 and the second pin 25 e on the thirdarm 23.

In the case of the present embodiment, the mounting angle α and themounting length ratio should be within the ±20-40 degrees range for αand within ⅕-⅓ of the mounting length ratio, from the viewpoint such asthe required torque for the driving sources M1, M2.

The appropriate ranges of α and can be provided by a specific numericalanalysis, with arm length, arm weight, driving torque of the driveshaft, friction in the spindle and other factors being set asparameters. Unless the positions of the first pin 25 d and the secondpin 25 e are adjusted so that the mounting angle α and mounting lengthratio fall within the above ranges, there will be a problem that thetorque of the driving sources M1, M2 must be raised.

FIG. 13A is a side sectional view illustrating the attitude controlmechanism of the articulating mechanism according to the presentembodiment; FIG. 13B is a sectional view taken along the C-C line inFIG. 13A; and FIG. 13C is a sectional view taken along the D-D line inFIG. 13A.

In the present embodiment, under the holder 30 of the articulatingmechanism 3, an attitude control mechanism 9 described below isarranged.

As shown in FIG. 13A, the attitude control mechanism 9 has spindles 27,28 and first to third cylindrical restraint pulleys 91, 92, and 93.

The spindle 27 is fixed in the position on centerline L5 of the holder30 and distant equally from the first carrier 31 a and the secondcarrier 31 b, supporting the third arm 23 and the fourth arm 24 throughtheir ends. The centerline L5 of the holder 30 connects the centers ofthe first carrier 31 a and the second carrier 31 b. Meanwhile, thespindle 28 is fixed in the position in parallel to the spindle 27 sothat it is distant from centerline L5 of the holder 30 and is distantequally from the first carrier 31 a and the second carrier 31 b.

The first restraint pulley 91 is fixed at the end of the third arm 23,where the spindle 27 penetrates. The second restraint pulley 92 is fixedat the end of the fourth arm 24, where the spindle 27 penetrates. Thethird restraint pulley 93 (rotator) is supported so that it may rotatewith no restriction around the spindle 28.

The diameters of those first to third restraint pulleys 91, 92 and 93are all the same.

Referring to FIGS. 13A and 13B, an endless restraint belt 94 is woundaround the first restraint pulley 91 and the third restraint pulley 93.This restraint belt 94 is fixed on the restraint pulleys 91, 93 by afastening screw 95, for example.

On the other hand, as shown in FIGS. 13A and 13C, a pair of restraintbelts 96, 97 are looped across over the second restraint pulley 92 andthe third restraint pulley 93. These restraint belts 96, 97 are fixed onthe second and third restraint pulleys 92, 93 by a, e.g., fasteningscrew 95.

The above configuration makes the first restraint pulley 91 and thethird restraint pulley 93 rotate in the same direction as much as thesame rotation. Meanwhile, the second restraint pulley 92 and the thirdrestraint pulley 93 rotate in the opposite direction as much as the samerotation.

FIG. 14 illustrates the operation of the first parallel link mechanismand the dead point escape mechanism (second parallel link mechanism)according to the present embodiment. In FIG. 14, the second and thirdlink members 22A, 23A are temporarily mounted on both ends of the linkmember 25 a of the second parallel link mechanism 10B for convenience ofexplanation. Actually, these link members 22A, 23A are replaced by thefirst link receiver 25 b of the second arm 22 and the second linkreceiver 25 c of the third arm 23.

Next, the operation of the present embodiment will be explained inreference to FIG. 11 and FIG. 14.

First, as shown in FIG. 14A, when the first drive shaft 11 and thesecond drive shaft 12 in the first parallel link mechanism 10A arerotated by a predetermined angle θ in the opposite direction so that theangle made by the first arm 21 and the second arm 22 increases toward180 degrees, which is the angle made when they exist on deadline L6connecting the dead points at both ends, the first arm 21 and the secondarm 22 rotate by the same angle θ in the opposite direction.

Then driven by the first parallel mechanism 10A, as the first and secondarms 21, 22 rotate, the third arm 23 rotates by an angle θ around thespindle 27, while the fourth arm 24 rotates by the same angle θ in theopposite direction of the third arm 23 around the spindle 27.

In the attitude control mechanism 9, the third restraint pulley 93 movesin the same direction of the first restraint pulley 91 and in theopposite direction of the second restraint pulley 92 by the same amountof rotation.

In other words, in the attitude control mechanism 9, the movement of thespindle 28 is restricted when the spindle 27 moves along with therotation of the third arm 23 and the fourth arm 24 so that the spindle28 moves along centerline L5 connecting the spindle 27 and the center ofthe holder 30. At the same time, centerline L5 of the holder 30 isaligned on transport line L7 connecting the first and second driveshafts 11, 12 and the spindle 27, which is the bisector of the angleformed by the third arm 23 and the fourth arm 24. Namely, the attitudeof the holder 30 is controlled to be symmetric along transport line L7by aligning it on the same transport line L7.

As a result, the carrier 31 attached to the holder 30 of thearticulating mechanism 3 moves straight on transport line L7. Whenreturning the carrier 31 of the holder 30 to the original position, thefirst drive shaft 11 and the second drive shaft 12 are rotated in thedirection opposite to that described above.

Meanwhile, in the second parallel link mechanism 10B (dead point escapemechanism 3), the second link member 22A and the third link member 23Aof the link member 25 a rotate keeping the mounting angle α against thesecond arm 22 and the third arm 23, respectively, when the first andsecond arms 21, 22 rotate.

Hereafter, the operation of the carrier 31 when it passes deadline L6 inthe configuration according to the present embodiment is described.

Referring to FIGS. 14B and 14C, when the angle formed by the first arm21 and the second arm 22 becomes 180 degrees, the angle formed by thethird and fourth arms 23, 24 also becomes 180 degrees, controlled by theparallel link mechanism. Then all the first to fourth arms 21, 22, 23and 24 are aligned on the same straight line.

In this situation, since the holder 30 has no initial velocity and thearm lengths of all first to fourth arms 21, 22, 23 and 24 are equal, theholder 30 cannot move back or forth staying right above the first andsecond drive shafts 11, 12 even if the first and second drive shafts 11,12 are rotated in the first parallel link mechanism 10A. In other words,the first arm 21 and the third arm 23 rotate in the same direction andthe second arm 22 and the fourth arm 24 rotate in the same direction aswell, the holder 30 cannot leave deadline L6.

However, since the second parallel link mechanism 10B is installed witha given tilt angle against the first parallel link mechanism 10A, therotary force of the second drive shaft 12 is transmitted to the thirdarm 23 through the second parallel link mechanism 10B.

Then, as shown in FIG. 14D, the carrier 31 of the holder 30 passesdeadline L6 and proceeds straight forward along transport line L7.

Note that the relationship between the first link mechanism 10A and thesecond link mechanism 10B situated at the dead point is the same as theabove, even if the angle made by the first arm 21 and the second arm 22becomes zero or 360 degrees and the first to fourth arms 21-24 are allaligned on the same transport line L7. On the other hand, when thesecond parallel link mechanism 10B reaches the dead point, in otherword, when the link member 25 a and the first arm 21 are aligned on thesame straight line, the movement of the holder 30 is not affected atall, because the first parallel link mechanism 10A is not situated atthe dead point.

In the present invention, the operation of replacing a treatedsemiconductor wafer by an untreated semiconductor wafer in the vacuumprocessing chamber is as shown in FIGS. 4A-4D and 5A-5C.

FIG. 15 illustrates another embodiment of the present invention.

In the aforementioned embodiment, the first and second carriers 31 a, 31b carry two semiconductor wafers 13 at the same time. However, it ispossible to apply this invention to transport apparatuses that carry asingle semiconductor wafer.

In the present embodiment, as shown in FIG. 15, the holder 30 has acarrier 32 on one side in its moving direction and this carrier 32 canaccept a single semiconductor wafer 13 thereon.

In this case, the carrier 32 may be installed on either side, front sideor back side, along the moving direction of the holder 30. However, foruse in multi-chamber systems, it is preferable to install the carrier 32on the front side of the moving direction of the holder 30, so that themoving distance becomes short.

According to the configuration of the above embodiment, it is possibleto provide a transport apparatus that can ensure the straight movementof the substrate with no increase in the number of necessary componentsor complexity in assembly and adjustment, eliminating the influence ofthe dead point escape mechanism upon the attitude control mechanism.

In particular, this embodiment is effective to downsize the transportapparatus because it can make the turning radius of the carrier small.The other configurations and resulting effects are not repeated herebecause they are the same as those described so far.

The invention is not limited only to the above embodiments, and can bemodified appropriately.

For example, in the above embodiment, the second parallel link mechanism10B is installed in the first parallel link mechanism 10A. However, itis possible to make the second parallel link mechanism 10B separate fromthe first parallel link mechanism 10A, extending the arms from the driveshafts 11, 12, which have been coupled with pins at both ends of thelink member 25 a in the above embodiment.

This configuration has an advantage in that it is not necessary to takeinto account the influence of the dimensional change of the link member25 a caused by external forces and heat upon the first parallel linkmechanism 10A.

In the above embodiment, the link member 25 a is added in between thefirst, second and third arms 21, 22 and 23 to form the second linkmechanism 10B. However, it is possible in this invention to form thesecond link mechanism 10B by adding the link member 25 a in between thefirst, second and fourth arms 21, 22 and 24.

Further in the above embodiment, the spindle 27 of the attitude controlmechanism 9 is positioned on transport line L7. However, the spindles27, 28 may be positioned symmetrically across centerline L5 of theholder 30. Then the holder 30 can move straight with higher precision,provided that changes in length due to heat are controlled to beuniform.

The restraint belts used in the attitude control mechanism may bereplaced by wires.

The transport apparatus according to the present invention may beapplied to a variety of apparatuses including vacuum processing systemsand modifications, improvements, and combinations can be made withdeparting from the scope of this invention.

As pointed out above, according to the invention, it is possible toprovide a transport apparatus having a simple configuration that canreduce its turning radius and transport semiconductor devices at highspeed.

Additionally, according to the invention, it is possible to provide atransport apparatus that can ensure the straight movement of thesubstrate with no increase in the number of necessary components orcomplexity in assembly and adjustment, eliminating the influence of thedead point escape mechanism upon the attitude control mechanism.

1-10. (canceled) 11: A transport apparatus for transporting substrates,the apparatus comprising: a first link mechanism formed by a pair ofdrive arms having respective drive shafts arranged at respective firstends thereof, the drive shafts being arranged coaxially and rotatable inopposite senses, and a pair of driven arms rotatably coupled torespective second ends of the paired drive arms; an attitude controlmechanism having a rotary member rotatable relative to spindlescoaxially supporting the respective second ends of the paired drivenarms and adapted to transmit rotary motions of the paired driven arms tothe rotary member at a same rate in opposite senses; and a dead pointescape mechanism having a second link mechanism formed by a link memberof a predetermined length and a pair of arm sections rotatably coupledto the opposite ends of the link member, one of the arm sections beingconnected to the drive shaft with a predetermined angle of inclinationrelative to the paired drive arms. 12: The transport apparatus accordingto claim 11, wherein the paired drive arms and the paired driven arms ofthe first link mechanism show a same and identical inter-joint distanceand a link member of the second link mechanism has an inter-jointdistance same as an inter-joint distance of the first link mechanism andis arranged in parallel with one of the paired drive arms. 13: Thetransport apparatus according to claim 11, wherein the second linkmechanism includes either one of the paired drive arm and either one ofthe paired driven arms. 14: The transport apparatus according to claim11, wherein the arm sections of the second link mechanism have a lengthratio between ⅕ and ⅓ to a paired drive arms of the first link mechanismand an angle of inclination between 20° and 40°. 15: The transportapparatus according to claim 11, further comprising: a holder forholding the substrates, the holder having a plurality of holdingsections; the rotary member of the attitude control mechanism beinglocated at a position separated from the holding sections by a samedistance.
 16. (canceled) 17: A vacuum processing system comprising: avacuum processing chamber; and a transport apparatus for conveyingsubstrates in a vacuum processing chamber; the transport apparatuscomprising: a first link mechanism formed by a pair of drive arms havingrespective drive shafts arranged at respective first ends thereof, thedrive shafts being arranged coaxially and rotatable in opposite senses,and a pair of driven arms rotatably coupled to respective second ends ofthe paired drive arms; an attitude control mechanism having a rotarymember rotatable relative to spindles coaxially supporting therespective second ends of the paired driven arms and adapted to transmitrotary motions of the paired driven arms to the rotary member at a samerate in opposite senses; and a dead point escape mechanism having asecond link mechanism formed by a link member of a predetermined lengthand a pair of arm sections rotatably coupled to the opposite ends of thelink member, one of the arm sections being fixed to the drive shaft witha predetermined angle of inclination relative to the paired drive arms.